U.S. patent application number 14/457762 was filed with the patent office on 2015-06-11 for load balancing in network deployments using unlicensed spectrum.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Ahmed Kamel SADEK.
Application Number | 20150163681 14/457762 |
Document ID | / |
Family ID | 53272507 |
Filed Date | 2015-06-11 |
United States Patent
Application |
20150163681 |
Kind Code |
A1 |
SADEK; Ahmed Kamel |
June 11, 2015 |
LOAD BALANCING IN NETWORK DEPLOYMENTS USING UNLICENSED SPECTRUM
Abstract
Systems and methods for interference mitigation in unlicensed
spectrum are disclosed. In an aspect, the methods and apparatus may
include requesting, by a first network entity, one or more user
equipments (UEs) to perform a plurality of frequency measurements,
wherein the plurality of frequency measurements comprises
measurements in a licensed spectrum and measurements in an
unlicensed spectrum. Further, the methods and apparatus may include
calculating a power back-off value based on the plurality of
frequency measurements. Moreover, the methods and apparatus may
include adjusting a cell coverage based on the power back-off value
such that the one or more UEs are outside the cell coverage.
Inventors: |
SADEK; Ahmed Kamel; (San
Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Family ID: |
53272507 |
Appl. No.: |
14/457762 |
Filed: |
August 12, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61914650 |
Dec 11, 2013 |
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Current U.S.
Class: |
455/446 |
Current CPC
Class: |
H04W 84/045 20130101;
H04W 16/08 20130101; H04W 16/14 20130101 |
International
Class: |
H04W 16/18 20060101
H04W016/18; H04W 16/14 20060101 H04W016/14 |
Claims
1. A method of wireless communication, comprising: requesting, by a
first network entity, one or more user equipments (UEs) to perform
a plurality of frequency measurements, wherein the plurality of
frequency measurements comprises measurements in a licensed
spectrum and measurements in an unlicensed spectrum; calculating a
power back-off value based on the plurality of frequency
measurements; and adjusting a cell coverage based on the power
back-off value such that the one or more UEs are outside the cell
coverage.
2. The method of claim 1, further comprising: determining, based at
least in part on the plurality of frequency measurements, whether
the one or more UEs have access to a second network entity over
both the licensed spectrum and the unlicensed spectrum, wherein
adjusting the cell coverage comprises reducing the cell coverage
when the one or more UEs have access to the second network entity
over both the licensed spectrum and the unlicensed spectrum.
3. The method of claim 1, further comprising: determining whether
the measurements in the licensed spectrum meet or exceed a first
threshold and whether the measurements in the unlicensed spectrum
meet or exceed a second threshold, wherein the one or more UEs
corresponding to the measurements in the licensed spectrum that
meet or exceed the first threshold and the measurements in the
unlicensed spectrum that meet or exceed the second threshold are
designated to an offload set, and wherein calculating the power
back-off value based on the plurality of frequency measurements
comprises calculating the power back-off value based on the
plurality of frequency measurements performed by the one or more
UEs designated to the offload set.
4. The method of claim 3, wherein adjusting the cell coverage based
on the power back-off value such that the one or more UEs are
outside the cell coverage comprises reducing the cell coverage such
that the one or more UEs designated to the offload set are outside
the cell coverage.
5. The method of claim 1, wherein adjusting the cell coverage based
on the power back-off value such that the one or more UEs are
outside the cell coverage causes the one or more UEs to attach to a
second network entity providing cell coverage over both the
licensed spectrum and the unlicensed spectrum.
6. The method of claim 1, wherein the requesting comprises
requesting the one or more UEs to perform a plurality of frequency
measurements on a second network entity.
7. The method of claim 1, wherein the measurements in the licensed
spectrum comprise measurements of intra-frequency Reference Signal
Received Power (RSRP) levels of a second network entity in the
licensed spectrum.
8. The method of claim 1, wherein the measurements in the licensed
spectrum comprise measurements of intra-frequency Reference Signal
Received Quality (RSRQ) levels of a second network entity in the
licensed spectrum.
9. The method of claim 1, wherein the measurements in the
unlicensed spectrum comprise measurements of inter-frequency RSRP
levels of a second network entity in the unlicensed spectrum.
10. The method of claim 1, wherein the measurements in the
unlicensed spectrum comprise measurements of inter-frequency RSRQ
levels of a second network entity in the unlicensed spectrum.
11. The method of claim 1, wherein the unlicensed spectrum
comprises a radio frequency band used in contention-based network
operations.
12. A computer program product, comprising: a non-transitory
computer-readable medium comprising code for: at least one
instruction executable to cause a computer to request one or more
user equipments (UEs) to perform a plurality of frequency
measurements, wherein the plurality of frequency measurements
comprises measurements in a licensed spectrum and an unlicensed
spectrum; at least one instruction executable to cause the computer
to calculate a power back-off value based at least in part on the
plurality of frequency measurements; and at least one instruction
executable to cause the computer to adjust a cell coverage based at
least in part on the power back-off value such that the one or more
UEs are outside the cell coverage.
13. An apparatus for wireless communication, comprising: means for
requesting one or more user equipments (UEs) to perform a plurality
of frequency measurements, wherein the plurality of frequency
measurements comprises measurements in a licensed spectrum and an
unlicensed spectrum; means for calculating a power back-off value
based at least in part on the plurality of frequency measurements;
and means for adjusting a cell coverage based at least in part on
the power back-off value such that the one or more UEs are outside
the cell coverage.
14. An apparatus for wireless communication, comprising: a memory
storing executable instructions; and a processor in communication
with the memory, wherein the processor is configured to execute
instructions to: request one or more user equipments (UEs) to
perform a plurality of frequency measurements, wherein the
plurality of frequency measurements comprises measurements in a
licensed spectrum and an unlicensed spectrum; calculate a power
back-off value based at least in part on the plurality of frequency
measurements; and adjust a cell coverage based at least in part on
the power back off value such that the one or more UEs are outside
the cell coverage.
15. The apparatus of claim 14, wherein the processor is further
configured to execute instructions to: determine, based at least in
part on the plurality of frequency measurements, whether the one or
more UEs have access to a second network entity over both the
licensed spectrum and the unlicensed spectrum, wherein adjusting
the cell coverage comprises reducing the cell coverage when the one
or more UEs have access to the second network entity over both the
licensed spectrum and the unlicensed spectrum.
16. The apparatus of claim 14, wherein the processor is further
configured to execute instructions to: determine whether the
measurements in the licensed spectrum meet or exceed a first
threshold and whether the measurements in the unlicensed spectrum
meet or exceed a second threshold, wherein the one or more UEs
corresponding to the measurements in the licensed spectrum that
meet or exceed the first threshold and the measurements in the
unlicensed spectrum that meet or exceed the second threshold are
designated to an offload set, and wherein calculating the power
back-off value based on the plurality of frequency measurements
comprises calculating the power back-off value based on the
plurality of frequency measurements performed by the one or more
UEs designated to the offload set.
17. The apparatus of claim 16, wherein adjusting the cell coverage
based on the power back-off value such that the one or more UEs are
outside the cell coverage comprises reducing the cell coverage such
that the one or more UEs designated to the offload set are outside
the cell coverage.
18. The apparatus of claim 14, wherein adjusting the cell coverage
based on the power back-off value such that the one or more UEs are
outside the cell coverage causes the one or more UEs to attach to a
second network entity providing cell coverage over both the
licensed spectrum and the unlicensed spectrum.
19. The apparatus of claim 14, wherein the requesting comprises
requesting the one or more UEs to perform a plurality of frequency
measurements on a second network entity.
20. The apparatus of claim 14, wherein the measurements in the
licensed spectrum comprise measurements of intra-frequency
Reference Signal Received Power (RSRP) levels of a second network
entity in the licensed spectrum.
21. The apparatus of claim 14, wherein the measurements in the
licensed spectrum comprise measurements of intra-frequency
Reference Signal Received Quality (RSRQ) levels of a second network
entity in the licensed spectrum.
22. The apparatus of claim 14, wherein the measurements in the
unlicensed spectrum comprise measurements of inter-frequency RSRP
levels of a second network entity in the unlicensed spectrum.
23. The apparatus of claim 14, wherein the measurements in the
unlicensed spectrum comprise measurements of inter-frequency RSRQ
levels of a second network entity in the unlicensed spectrum.
24. The apparatus of claim 14, wherein the unlicensed spectrum
comprises a radio frequency band used in contention-based network
operations.
Description
CLAIM OF PRIORITY UNDER 35 U.S.C .sctn.119
[0001] The present application for patent claims priority to U.S.
Provisional Application No. 61/914,650 entitled "METHODS AND
APPARATUS FOR LOAD BALANCING IN NETWORK DEPLOYMENTS USING
UNLICENSED SPECTRUM" filed Dec. 11, 2013, Qualcomm Ref. No.
140771P1, assigned to the assignee hereof and hereby expressly
incorporated by reference.
BACKGROUND
[0002] Aspects of this disclosure relate generally to
telecommunications, and more particularly to interference
mitigation.
[0003] A wireless communication network may be deployed to provide
various types of services (e.g., voice, data, multimedia services,
etc.) to users within a coverage area of the network. In some
implementations, one or more access points (e.g., corresponding to
different cells) provide wireless connectivity for access terminals
(e.g., cell phones) that are operating within the coverage of the
access point(s). In some implementations, peer devices provide
wireless connectively for communicating with one another.
[0004] Communication between devices in a wireless communication
network may be subject to interference. For a communication between
any two devices in a network, emissions of radio frequency (RF)
energy by a nearby device may interfere with reception of signals
at the other device. For example, a Long Term Evolution (LTE)
device operating in an unlicensed RF band that is also being used
by a Wi-Fi device may experience significant interference from the
Wi-Fi device, and/or can cause significant interference to the
Wi-Fi device.
[0005] Over-the-air interference detection is employed in some
wireless communication networks in an attempt to mitigate such
interference. For example, a device may periodically monitor (e.g.,
sniff) for energy in the RF band used by the device. Upon detection
of any kind of energy, the device may back-off and refrain from
accessing the RF band for a period of time.
[0006] In practice, however, there may be problems with such a
back-off or "listen-before-talk" (LBT) approach, at least in its
conventional implementation. For example, for an LTE system
operating in an unlicensed band with a Wi-Fi co-channel scenario
where it is desired to avoid interference from Wi-Fi, the detected
energy in the band may not be from a Wi-Fi device, or may not be
substantial. In addition, the detected energy in the band may
simply be adjacent channel leakage. Consequently, an LTE device may
back off transmissions in the band even when there is no Wi-Fi
interference. In some wireless communication networks, inefficient
utilization of available communication resources, particularly
identification resources for configuration of subframes during
radar detection, may lead to degradations in wireless
communication. Even more, the foregoing inefficient resource
utilization inhibits network devices from achieving higher wireless
communication quality. Thus, improvements in interference
mitigation are desired.
SUMMARY
[0007] The following presents a simplified summary of one or more
aspects in order to provide a basic understanding of such aspects.
This summary is not an extensive overview of all contemplated
aspects, and is intended to neither identify key or critical
elements of all aspects nor delineate the scope of any or all
aspects. Its sole purpose is to present some concepts of one or
more aspects in a simplified form as a prelude to the more detailed
description that is presented later.
[0008] Systems and methods for interference mitigation in
unlicensed spectrum are disclosed. In an aspect, the method may
include requesting, by a first network entity, one or more user
equipments (UEs) to perform a plurality of frequency measurements,
wherein the plurality of frequency measurements comprises
measurements in a licensed spectrum and measurements in an
unlicensed spectrum. Further, the method may include calculating a
power back-off value based on the plurality of frequency
measurements. Moreover, the method may include adjusting a cell
coverage based on the power back-off value such that the one or
more UEs are outside the cell coverage.
[0009] Further aspects provide a computer program product for
interference mitigation in unlicensed spectrum comprising at least
one instruction executable to cause a computer to request, by a
first network entity, one or more user equipments (UEs) to perform
a plurality of frequency measurements, wherein the plurality of
frequency measurements comprises measurements in a licensed
spectrum and measurements in an unlicensed spectrum; calculate a
power back-off value based on the plurality of frequency
measurements; and adjust a cell coverage based on the power
back-off value such that the one or more UEs are outside the cell
coverage.
[0010] Additional aspects provide an apparatus for interference
mitigation in unlicensed spectrum comprises means for requesting,
by a first network entity, one or more user equipments (UEs) to
perform a plurality of frequency measurements, wherein the
plurality of frequency measurements comprises measurements in a
licensed spectrum and measurements in an unlicensed spectrum;
calculating a power back-off value based on the plurality of
frequency measurements; and adjusting a cell coverage based on the
power back-off value such that the one or more UEs are outside the
cell coverage.
[0011] In an additional aspect, an apparatus for interference
mitigation in unlicensed spectrum comprises a memory storing
executable instructions and a processor in communication with the
memory, wherein the processor is configured to execute the
instructions to request, by a first network entity, one or more
user equipments (UEs) to perform a plurality of frequency
measurements, wherein the plurality of frequency measurements
comprises measurements in a licensed spectrum and measurements in
an unlicensed spectrum; calculate a power back-off value based on
the plurality of frequency measurements; and adjust a cell coverage
based on the power back-off value such that the one or more UEs are
outside the cell coverage.
[0012] Various aspects and features of the disclosure are described
in further detail below with reference to various examples thereof
as shown in the accompanying drawings. While the present disclosure
is described below with reference to various examples, it should be
understood that the present disclosure is not limited thereto.
Those of ordinary skill in the art having access to the teachings
herein will recognize additional implementations, modifications,
and examples, as well as other fields of use, which are within the
scope of the present disclosure as described herein, and with
respect to which the present disclosure may be of significant
utility.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The accompanying drawings are presented to aid in the
description of various aspects of the disclosure and are provided
solely for illustration of the aspects and not limitation
thereof.
[0014] FIG. 1 is a block diagram illustrating an example of several
aspects of a communication system employing co-located radios.
[0015] FIG. 2 shows a downlink frame structure used in LTE.
[0016] FIG. 3 is a diagram illustrating an example of carrier sense
adaptive transmission (CSAT) time division multiplexing (TDM) duty
cycling.
[0017] FIG. 4 is a schematic diagram illustrating an example of a
communication network including an aspect of a network entity that
may adjust cell coverage.
[0018] FIG. 5 is a schematic diagram illustrating an example of an
aspect of load balancing components in a network entity.
[0019] FIG. 6 is a diagram illustrating an example a range expanded
cellular region in a heterogeneous network;
[0020] FIG. 7 is a diagram illustrating an example of a carrier
aggregation network according to an aspect of the present
disclosure;
[0021] FIG. 8 is a diagram illustrating an example of a
supplemental downlink (DL) network according to an aspect of the
present disclosure
[0022] FIG. 9 is a flow diagram illustrating an example method of
an aspect for load balancing in a communication network.
[0023] FIG. 10 is a flow diagram illustrating an example method of
another aspect for load balancing in a communication network.
[0024] FIG. 11 is a block diagram illustrating an example of
several sample aspects of components that may be employed in
communication nodes.
[0025] FIG. 12 is a diagram illustrating an example of a wireless
communication system.
[0026] FIG. 13 is a diagram illustrating an example of a wireless
communication system including small cells.
[0027] FIG. 14 is a diagram illustrating examples of coverage areas
for wireless communication.
[0028] FIG. 15 is a block diagram illustrating an example of
several aspects of communication components.
[0029] FIGS. 16 and 17 are block diagrams illustrating an example
of several aspects of apparatuses configured to support
communication as taught herein.
DETAILED DESCRIPTION
[0030] The disclosure relates in some aspects to interference
mitigation in wireless communication systems. Specifically, in some
wireless communication systems, network entities may provide
coverage on a licensed spectrum and an unlicensed spectrum while
other network entities may only provide coverage on the licensed
spectrum. Accordingly, a user equipment (UE), operating either in
carrier aggregation (CA) or supplementary downlink (SDL) mode in
support of LTE/LTE Advanced over an unlicensed spectrum in addition
to LTE/LTE Advanced over a licensed spectrum, has to attach with a
primary cell first. For example, the UE may have to attach to a
primary cell with a network entity that only provides coverage in
the licensed spectrum even though the UE is within coverage of
another network entity that provides coverage in both the licensed
spectrum and the unlicensed spectrum. Currently, coverage range
extension (CRE) and enhanced inter-cell interference coordination
(eICIC) may be applied to extend the coverage of a network entity
that provides coverage in both the licensed spectrum and the
unlicensed spectrum. However, extending coverage in this manner may
not be sufficient due to the other network entity being designated
as the primary cell. In some instances, a UE served by a network
entity designated as the primary cell may come in to range of
another network entity providing coverage in both the licensed
spectrum and the unlicensed spectrum. However, since the other
network entity is not designated as the primary, the UE may be
prevented from attaching to it. Additionally, the other network
entity providing coverage in both spectrums may be moved to a
dedicated channel on the primary cell. However, in some instances a
dedicated channel for the other network entity may not exist. As a
result, the unlicensed spectrum may not be utilized since the UE
has access to only a single channel on the primary cell. Hence, by
limiting unlicensed spectrum utilization the UE may not be able to
optimize its downlink and uplink capabilities.
[0031] As such, the present methods and apparatus may adjust a cell
coverage of a network entity that only provides coverage in the
licensed spectrum, so as to provide the UE with the capability of
attaching to another network entity that provides coverage in both
the licensed spectrum and the unlicensed spectrum. A network entity
that provides coverage in both licensed spectrum and the unlicensed
spectrum allows for higher data rates and an enhanced broadband
experience. Accordingly, in some aspects, the present methods and
apparatus may provide an efficient solution, as compared to current
solutions, to enable a network entity to determine that a UE is
within cell coverage of another network entity that provides
coverage in both the licensed spectrum and the unlicensed spectrum
and to adjust its own cell coverage to enable the UE to attach to
that other network entity.
[0032] Aspects of the disclosure are provided in the following
description and related drawings directed to specific disclosed
aspects. Alternate aspects may be devised without departing from
the scope of the disclosure. Additionally, well-known aspects of
the disclosure may not be described in detail or may be omitted so
as not to obscure more relevant details. Further, many aspects are
described in terms of sequences of actions to be performed by, for
example, elements of a computing device. It will be recognized that
various actions described herein can be performed by specific
circuits (e.g., application specific integrated circuits (ASICs)),
by program instructions being executed by one or more processors,
or by a combination of both. Additionally, these sequence of
actions described herein can be considered to be embodied entirely
within any form of computer readable storage medium having stored
therein a corresponding set of computer instructions that upon
execution would cause an associated processor to perform the
functionality described herein. Thus, the various aspects of the
disclosure may be embodied in a number of different forms, all of
which have been contemplated to be within the scope of the claimed
subject matter. In addition, for each of the aspects described
herein, the corresponding form of any such aspects may be described
herein as, for example, "logic configured to" perform the described
action.
[0033] FIG. 1 illustrates several nodes of a sample communication
system 100 (e.g., a portion of a communication network). For
illustration purposes, various aspects of the disclosure will be
described in the context of one or more access terminals, access
points, and network entities that communicate with one another. It
should be appreciated, however, that the teachings herein may be
applicable to other types of apparatuses or other similar
apparatuses that are referenced using other terminology. For
example, in various implementations access points may be referred
to or implemented as base stations, NodeBs, eNodeBs, Home NodeBs,
Home eNodeBs, small cells, macro cells, femto cells, and so on,
while access terminals may be referred to or implemented as user
equipment (UEs), mobile stations, and so on.
[0034] Access points in the system 100 provide access to one or
more services (e.g., network connectivity) for one or more wireless
terminals (e.g., the access terminal 102 or the access terminal
104) that may be installed within or that may roam throughout a
coverage area of the system 100, each of which may include load
balancing component 320 (FIG. 4) configured to adjust a cell
coverage of an access point (e.g., network entity 306) that only
provides coverage in the licensed spectrum, so as to provide an
access terminal (e.g., UE 302 in FIG. 4) with the capability of
attaching to another access point (e.g., network entity 304 in FIG.
4) that provides coverage in both the licensed spectrum and the
unlicensed spectrum. For example, at various points in time the
access terminal 102 may connect to the access point 106 or some
other access point in the system 100 (not shown). Similarly, the
access terminal 104 may connect to the access point 108 or some
other access point.
[0035] One or more of the access points may communicate with one or
more network entities (represented, for convenience, by the network
entities 110), including each other, to facilitate wide area
network connectivity. Two or more of such network entities may be
co-located and/or two or more of such network entities may be
distributed throughout a network.
[0036] A network entity may take various forms such as, for
example, one or more radio and/or core network entities. Thus, in
various implementations the network entities 110 may represent
functionality such as at least one of: network management (e.g.,
via an operation, administration, management, and provisioning
entity), call control, session management, mobility management,
gateway functions, interworking functions, or some other suitable
network functionality. In some aspects, mobility management relates
to: keeping track of the current location of access terminals
through the use of tracking areas, location areas, routing areas,
or some other suitable technique; controlling paging for access
terminals; and providing access control for access terminals.
[0037] When the access point 106 (or any other devices in the
system 100) uses a first RAT to communicate on a given resource,
this communication may be subjected to interference from nearby
devices (e.g., the access point 108 and/or the access terminal 104)
that use a second RAT to communicate on that resource. For example,
communication by the access point 106 via LTE on a particular
unlicensed RF band may be subject to interference from Wi-Fi
devices operating on that band. For convenience, LTE on an
unlicensed RF band may be referred to herein as LTE/LTE Advanced in
unlicensed spectrum, or simply LTE in the surrounding context.
[0038] In some systems, LTE in unlicensed spectrum may be employed
in a standalone configuration, with all carriers operating
exclusively in an unlicensed portion of the wireless spectrum
(e.g., LTE Standalone). In other systems, LTE in unlicensed
spectrum may be employed in a manner that is supplemental to
licensed band operation by providing one or more unlicensed
carriers operating in the unlicensed portion of the wireless
spectrum in conjunction with an anchor licensed carrier operating
in the licensed portion of the wireless spectrum (e.g., LTE
Supplemental DownLink (SDL)). In either case, carrier aggregation
may be employed to manage the different component carriers, with
one carrier serving as the Primary Cell (PCell) for the
corresponding UE (e.g., an anchor licensed carrier in LTE SDL or a
designated one of the unlicensed carriers in LTE Standalone) and
the remaining carriers serving as respective Secondary Cells
(SCells). In this way, the PCell may provide an FDD paired downlink
and uplink (licensed or unlicensed), and each SCell may provide
additional downlink capacity as desired.
[0039] In general, LTE utilizes orthogonal frequency division
multiplexing (OFDM) on the downlink and single-carrier frequency
division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM
partition the system bandwidth into multiple (K) orthogonal
subcarriers, which are also commonly referred to as tones, bins,
etc. Each subcarrier may be modulated with data. In general,
modulation symbols are sent in the frequency domain with OFDM and
in the time domain with SC-FDM. The spacing between adjacent
subcarriers may be fixed, and the total number of subcarriers (K)
may be dependent on the system bandwidth. For example, K may be
equal to 128, 256, 512, 1024 or 2048 for system bandwidth of 1.25,
2.5, 5, 10 or 20 megahertz (MHz), respectively. The system
bandwidth may also be partitioned into subbands. For example, a
subband may cover 1.08 MHz, and there may be 1, 2, 4, 8 or 16
subbands for system bandwidth of 1.25, 2.5, 5, 10 or 20 MHz,
respectively.
[0040] FIG. 2 shows a downlink frame structure 200 used in LTE. The
transmission timeline for the downlink may be partitioned into
units of radio frames 202, 204, 206. Each radio frame may have a
predetermined duration (e.g., 10 milliseconds (ms)) and may be
partitioned into 10 subframes 208 with indices of 0 through 9. Each
subframe may include two slots, e.g., slots 210. Each radio frame
may thus include 20 slots with indices of 0 through 19. Each slot
may include L symbol periods, e.g., 7 symbol periods 212 for a
normal cyclic prefix (CP), as shown in FIG. 2, or 6 symbol periods
for an extended cyclic prefix. The normal CP and extended CP may be
referred to herein as different CP types. The 2L symbol periods in
each subframe may be assigned indices of 0 through 2L-1. The
available time frequency resources may be partitioned into resource
blocks. Each resource block may cover N subcarriers (e.g., 12
subcarriers) in one slot.
[0041] In LTE, the access point (referred to as an eNB) may send a
Primary Synchronization Signal (PSS) and a Secondary
Synchronization Signal (SSS) for each cell in the eNB. The primary
and secondary synchronization signals may be sent in symbol periods
6 and 5, respectively, in each of subframes 0 and 5 of each radio
frame with the normal cyclic prefix, as shown in FIG. 2. The
synchronization signals may be used by the access terminals
(referred to as UEs) for cell detection and acquisition. The eNB
may send a Physical Broadcast Channel (PBCH) in symbol periods 0 to
3 in slot 1 of subframe 0. The PBCH may carry certain system
information.
[0042] The eNB may send a Cell-specific Reference Signal (CRS) for
each cell in the eNB. The CRS may be sent in symbols 0, 1, and 4 of
each slot in case of the normal cyclic prefix, and in symbols 0, 1,
and 3 of each slot in case of the extended cyclic prefix. The CRS
may be used by UEs for coherent demodulation of physical channels,
timing and frequency tracking, Radio Link Monitoring (RLM),
Reference Signal Received Power (RSRP), and Reference Signal
Received Quality (RSRQ) measurements, etc.
[0043] The eNB may send a Physical Control Format Indicator Channel
(PCFICH) in only a portion of the first symbol period of each
subframe, although depicted in the entire first symbol period in
FIG. 2. The PCFICH may convey the number of symbol periods (M) used
for control channels, where M may be equal to 1, 2 or 3 and may
change from subframe to subframe. M may also be equal to 4 for a
small system bandwidth, e.g., with less than 10 resource blocks. In
the example shown in FIG. 2, M=3. The eNB may send a Physical HARQ
Indicator Channel (PHICH) and a Physical Downlink Control Channel
(PDCCH) in the first M symbol periods of each subframe (M=3 in FIG.
2). The PHICH may carry information to support hybrid automatic
retransmission (HARQ). The PDCCH may carry information on resource
allocation for UEs and control information for downlink channels.
Although not shown in the first symbol period in FIG. 2, it is
understood that the PDCCH and PHICH may also be included in the
first symbol period. Similarly, the PHICH and PDCCH may also both
be in the second and third symbol periods, although not shown that
way in FIG. 2. The eNB may send a Physical Downlink Shared Channel
(PDSCH) in the remaining symbol periods of each subframe. The PDSCH
may carry data for UEs scheduled for data transmission on the
downlink. The various signals and channels in LTE are described in
3GPP TS 36.211, entitled "Evolved Universal Terrestrial Radio
Access (E-UTRA); Physical Channels and Modulation," which is
publicly available.
[0044] The eNB may send the PSS, SSS and PBCH in the center 1.08
MHz of the system bandwidth used by the eNB. The eNB may send the
PCFICH and PHICH across the entire system bandwidth in each symbol
period in which these channels are sent. The eNB may send the PDCCH
to groups of UEs in certain portions of the system bandwidth. The
eNB may send the PDSCH to specific UEs in specific portions of the
system bandwidth. The eNB may send the PSS, SSS, PBCH, PCFICH and
PHICH in a broadcast manner to all UEs, may send the PDCCH in a
unicast manner to specific UEs, and may also send the PDSCH in a
unicast manner to specific UEs.
[0045] A number of resource elements may be available in each
symbol period. Each resource element may cover one subcarrier in
one symbol period and may be used to send one modulation symbol,
which may be a real or complex value. Resource elements not used
for a reference signal in each symbol period may be arranged into
resource element groups (REGs). Each REG may include four resource
elements in one symbol period. The PCFICH may occupy four REGs,
which may be spaced approximately equally across frequency, in
symbol period 0. The PHICH may occupy three REGs, which may be
spread across frequency, in one or more configurable symbol
periods. For example, the three REGs for the PHICH may all belong
in symbol period 0 or may be spread in symbol periods 0, 1 and 2.
The PDCCH may occupy 9, 18, 32 or 64 REGs, which may be selected
from the available REGs, in the first M symbol periods. Only
certain combinations of REGs may be allowed for the PDCCH.
[0046] A UE may know the specific REGs used for the PHICH and the
PCFICH. The UE may search different combinations of REGs for the
PDCCH. The number of combinations to search is typically less than
the number of allowed combinations for the PDCCH. An eNB may send
the PDCCH to the UE in any of the combinations that the UE will
search. A UE may be within the coverage of multiple eNBs. One of
these eNBs may be selected to serve the UE. The serving eNB may be
selected based on various criteria such as received power, path
loss, signal-to-noise ratio (SNR), etc.
[0047] Returning to FIG. 1, the disclosure relates in some aspects
to techniques referred to herein as carrier sense adaptive
transmission (CSAT), which may be used to facilitate co-existence
between different technologies operating on a commonly used
resource (e.g., a particular unlicensed RF band or co-channel). The
access point 106 includes co-located radios (e.g., transceivers)
112 and 114. The radio 112 uses a second RAT (e.g., LTE) to
communicate. The radio 114 is capable of receiving signals using a
first RAT (e.g., Wi-Fi). In addition, an interface 116 enables the
radios 112 and 114 to communicate with one another.
[0048] These co-located radios are leveraged to enable a carrier
sense multiple access-like (CSMA-like) mode of operation whereby
the radio 114 repeatedly (e.g., periodically) conducts measurements
on the co-channel. Based on these measurements, the radio 112
determines the extent to which the co-channel is being utilized by
devices operating on the first RAT. The radio 112 is thus able to
adapt its communication on the channel (using the second RAT)
according to the resource utilization.
[0049] For example, if the utilization of the resource by Wi-Fi
devices is high, an LTE radio may adjust one or more transmission
parameters that the LTE radio uses to communicate via the
co-channel such that usage of the co-channel by the LTE radio is
reduced. For example, the LTE radio may reduce its transmit duty
cycle, transmit power, or frequency allocation.
[0050] Conversely, if the utilization of the resource by Wi-Fi
devices is low, an LTE radio may adjust one or more transmission
parameters that the LTE radio uses to communicate via the
co-channel such that usage of the co-channel by the LTE radio is
increased. For example, the LTE radio may increase its transmit
duty cycle, transmit power, or frequency allocation.
[0051] The disclosed scheme may provide several advantages. For
example, by adapting communication based on signals associated with
the first RAT, the second RAT may be configured to only react to
utilization of the co-channel by devices that use the first RAT.
Thus, interference by other devices (e.g., non-Wi-Fi devices) or
adjacent channel interference may be ignored, if desired. As
another example, the scheme enables a device that uses a given RAT
to control how much protection is to be afforded to co-channel
communications by devices that use another RAT. Also, such a scheme
may be implemented in an LTE system without changing the LTE PHY or
MAC. For example, these changes may be implemented by simply
changing LTE software.
[0052] In some aspects, the advantages discussed herein may be
achieved by adding a Wi-Fi chip or similar functionality to an LTE
access point. If desired, a low functionality Wi-Fi circuit may be
employed to reduce costs (e.g., the Wi-Fi circuit simply providing
low-level sniffing).
[0053] As used herein, the term co-located (e.g., radios, access
points, transceivers, etc.) may include in various aspects, one or
more of, for example: components that are in the same housing;
components that are hosted by the same processor; components that
are within a defined distance of one another, or components that
are connected via an interface (e.g., an Ethernet switch) where the
interface meets the latency requirements of any required
inter-component communication (e.g., messaging).
[0054] FIG. 3 illustrates an example of CSAT Time Division
Multiplexed (TDM) duty cycling for LTE in unlicensed spectrum.
During time T.sub.ON, transmission on the unlicensed RF band is
enabled, which may be referred to as a CSAT ON period. During time
T.sub.OFF, transmission on the unlicensed RF band is disabled,
which may be referred to as a CSAT OFF period, to enable a
co-located Wi-Fi radio to conduct measurements. In this way, TDM
communication duty cycling for LTE in unlicensed spectrum may be
implemented to create adaptable TDM transmission patterns. Aspects
of the disclosure related to load balancing may also apply to LTE
in unlicensed spectrum that is implemented using techniques
different from CSAT TDM.
[0055] Referring to FIG. 4, in an aspect, a wireless communication
system 300 includes at least one UE 302, corresponding to access
terminal 102/104 (FIG. 1) in communication coverage of at least a
network entity 304 and a network entity 306, each of which may
correspond with access point 106 and/or 108 (FIG. 1). UE 302 may
communicate with network 308 via one or both of network entity 304
and network entity 306. In some aspects, multiple UEs including UE
302 may be in communication coverage with one or more network
entities, including network entity 304 and network entity 306. For
instance, UE 302 may communicate with network entity 304 on or
using one or more communication channels 310 on the licensed
spectrum, and one or more communication channels 311 on the
unlicensed spectrum. In one aspect, the unlicensed spectrum may
refer to a radio frequency band used for contention-based network
operations. Further, for example, UE 302 may communicate with
network entity 306 on or using one or more communication channels
312 on the licensed spectrum.
[0056] It should be understood that UE 302 may communicate with one
or more cells included or deployed at one or both network entity
304 and network entity 306. That is, UE 302 may select or reselect
from one cell at network entity 304 to another cell at network
entity 304. In other aspects, network entity 304 may alternatively
be referred to as a network entity with which UE 302 maintains an
RRC connected state. Additionally, UE 302 may transmit and/or
receive wireless communication to and/or from network entity 304
and/or network entity 306. For example, such wireless information
may include, but is not limited to, information related frequency
measurements.
[0057] In some aspects, UE 302 may also be referred to by those
skilled in the art (as well as interchangeably herein) as a mobile
station, a subscriber station, a mobile unit, a subscriber unit, a
wireless unit, a remote unit, a mobile device, a wireless device, a
wireless communications device, a remote device, a mobile
subscriber station, an access terminal, a mobile terminal, a
wireless terminal, a remote terminal, a handset, a terminal, a user
agent, a mobile client, a client, a wireless transmit/receive unit,
a device for the Internet of Things (IoT), or some other suitable
terminology.
[0058] Additionally, network entity 304 and network entity 306 may
be a macrocell, picocell, femtocell, access point, relay, Node B,
mobile Node B, eNode B (eNB), UE (e.g., communicating in
peer-to-peer or ad-hoc mode with UE 302), or substantially any type
of component that can communicate with UE 302 to provide wireless
network access at the UE 302.
[0059] According to the present aspects, network entity 306 may
include load balancing component 320, which may be configured to
determine that a UE (e.g., UE 302) may be served by a network
entity (e.g., network entity 304) that provides coverage in both
the licensed spectrum and unlicensed spectrum. For example, load
balancing component 320 may request one or more UEs (e.g., UE 302)
to perform a plurality of frequency measurements, calculate a power
back-off value based at least in part on the plurality of frequency
measurements; and adjust a cell coverage (e.g., second cell) based
at least in part on the power back-off value. Hence, one or more
UEs (e.g., UE 302) may no longer be located within coverage of the
second cell (e.g., network entity 306). As such, the one or more
UEs (e.g., UE 302) may be free to attach to another cell, such as
the network entity (e.g., network entity 304). As a result, the one
or more UEs (e.g., UE 302) may be able to utilize both licensed
spectrum and unlicensed spectrum provided by the network entity
(e.g., network entity 304).
[0060] In an aspect, load balancing component 320 may include
requesting component 330, which may be configured to transmit a
request to one or more UEs (e.g., UE 302) to perform a plurality of
frequency measurements. For example, requesting component 330 may
be configured to transmit a request to one or more UEs (e.g., UE
302) to perform measurements on both the licensed spectrum and
unlicensed spectrum for one or more cells (e.g., network entity
304). The measurements may include measuring intra-frequency
Reference Signal Received Power (RSRP) levels of one or more
network entities in the licensed spectrum and inter-frequency RSRP
levels of the one or more network entities. Further, the
measurements may include measuring intra-frequency Reference Signal
Received Quality (RSRQ) levels of one or more network entities in
the licensed spectrum and inter-frequency RSRQ levels of the one or
more network entities. Additionally, UE 302 may be in a CA or SDL
connected state with the second cell (e.g., network entity 306)
during such measurements.
[0061] Additionally, load balancing component 320 and/or requesting
component 330 may be configured to receive the plurality of
frequency measurements from the one or more UEs (e.g., UE 302). For
example, requesting component 330 may be configured to receive
measurements including intra-frequency RSRP levels, inter-frequency
RSRP levels, intra-frequency RSRQ levels, and inter-frequency RSRQ
levels from the one or more UEs (e.g., UE 302) in response to
transmitting the request.
[0062] Load balancing component 320 may optionally include
determining component 350, which may be configured to determine
whether the one or more UEs (e.g., UE 302) have access to the
licensed spectrum and the unlicensed spectrum provided by one or
more network entities (e.g., network entity 304) based at least in
part on the plurality of frequency measurements. For example,
determining component 350 may be configured to receive the
plurality of measurements from requesting component 330, and
determine based on the presence of measurements including
intra-frequency RSRP levels, inter-frequency RSRP levels,
intra-frequency RSRQ levels, and inter-frequency RSRQ levels
whether the one or more UEs (e.g., UE 302) have access to the
licensed spectrum and the unlicensed spectrum.
[0063] In additional aspects, load balancing component 320 may
optionally include comparing component 360, which may be configured
to determine whether any one of the plurality of measurements meets
or exceeds a threshold (e.g., a power threshold). For example,
comparing component 360 may be configured to determine whether any
one of the plurality of measurements meets or exceeds a power
threshold prior to calculating the power-back off value based on
the plurality of measurements. For example, comparing component 360
may receive the measurements from requesting component 330 or
determining component 350, and before transmitting them, may
compare them against the power threshold to determine whether the
one or more UEs (e.g., UE 302) have the potential to be offloaded
to one or more network entities (e.g., network entity 304).
[0064] Further, load balancing component 320 may include
calculating component 370, which may be configured to calculate a
power back-off value (e.g., an amount by which transmission power
is to be reduced) based at least in part on the plurality of
frequency measurements. In some aspects, the calculating component
370 may receive the measurements from comparing component 360. As
such, calculating component 370 may base its calculations on
intra-frequency RSRP levels, inter-frequency RSRP levels,
intra-frequency RSRQ levels, and inter-frequency RSRQ levels.
Moreover, calculating component 370 may base its calculation of the
power back-off value on whether the one or more UEs (e.g., UE 302)
are in Network Listen mode on both the licensed spectrum and
unlicensed spectrum. As such, calculating component 370 may
calculate only based on the one or more of the plurality of
measurements that comparing component 360 determined met or
exceeded the power threshold. Therefore, power back-off
calculations may be performed only for UEs (e.g., UE 302) having
access to both licensed spectrum and unlicensed spectrum.
[0065] Additionally, load balancing component 320 may include
coverage component 380, which may be configured to adjust a cell
coverage of network entity 306 based at least in part on the power
back-off value calculated by calculating component 370.
Specifically, for example, coverage component 380 may be configured
to adjust (e.g., reduce) the transmit power, so one or more UEs
(e.g., UE 302) may no longer be located within coverage of the
network entity (e.g., network entity 306). As such, the one or more
UEs (e.g., UE 302) may be free to attach to another cell, such as
the network entity (e.g., network entity 304). As a result, the one
or more UEs (e.g., UE 302) will be able to utilize both licensed
spectrum and unlicensed spectrum provided by the network entity
(e.g., network entity 304).
[0066] FIG. 5 is a schematic diagram of an aspect of the load
balancing component 320, which reside in network entity 306 of FIG.
4. Generally, load balancing component 320 may reside at a network
entity (e.g., network entities 304 and/or 306) and may be
configured to manage load balancing parameters for the plurality of
UEs (e.g., UE 302) assigned to the network entity 306.
[0067] Specifically in an aspect, load balancing component 320 may
include requesting component 330, which may be configured to
request one or more UEs (e.g., UE 302 in FIG. 4) to perform a
plurality of frequency measurements 332. For example, requesting
component 330 may request one or more UEs that are located within
its cell coverage area to perform frequency measurements 332 in a
licensed spectrum 334 and an unlicensed spectrum 340. In an
instance, requesting component 330 may request one or more UEs to
perform frequency measurements 332 in the licensed spectrum 334 and
unlicensed spectrum 340 of neighbor cells (e.g., a second network
entity such as network entity 304 if load balancing component 320
resides at network entity 306 as shown in FIG. 4). In some
instances, the frequency measurements 332 may comprise measurements
of intra-frequency Reference Signal Received Power (RSRP) levels
336 and of intra-frequency Reference Signal Received Quality (RSRQ)
levels 338 of a neighbor cell (e.g., network entity 304) in the
licensed spectrum 334. Additionally, the frequency measurements 332
may comprise measurements of inter-frequency RSRP levels 342 and of
inter-frequency RSRQ levels 344 of a neighbor cell (e.g., network
entity 304) in the unlicensed spectrum 340. These frequency
measurements 332 of RSRP 336 and RSRQ 338 levels correspond to the
signal strength and quality of neighbor cells. In general, RSRP
corresponds to the average received power over the resource
elements that carry cell-specific reference signals within certain
frequency bandwidth. RSRQ corresponds to the quality of the
received reference signal, and in certain instances, provides
additional information when the RSRP is not sufficient to make a
reliable handover or cell reselection decision. RSRP may be
applicable in both Radio Resource Control (RRC) idle and RRC
connected modes, while RSRQ may be only applicable in RRC connected
mode. In the procedure of cell selection and cell reselection in
idle mode, RSRP may be used.
[0068] In another aspect, load balancing component 320 may
optionally include determining component 350, which may be
configured to determine whether the one or more UEs (e.g., UE 302
in FIG. 4) have access to a second network entity (e.g., network
entity 304) over both the licensed spectrum 334 and the unlicensed
spectrum 340. For example, determining component 350 may determine
whether UE 302 has access to network entity 304 based on the
frequency measurements 332. In an instance, requesting component
330 may receive the plurality of frequency measurements 332 from UE
302 including measurements of intra-frequency RSRP 336 and RSRQ 338
levels and measurements of inter-frequency RSRP 342 and RSRQ 344
levels, and determining component 350 may make a determination
whether UE 302 would be able to select an neighbor cell to attach
to (e.g., network entity 304). The neighbor cell must provide
coverage on both the licensed spectrum 334 and the unlicensed
spectrum 340 (e.g., communication channels 310 and 311).
Determining component 350 may determine whether the frequency
measurements 332 indicate whether network entity 304 provides cell
coverage for UE 302. In instances where determining component 350
determines that frequency measurements 332 indicate that network
entity 304 does not provide cell coverage for UE 302, calculating
component 370 is prevented from calculating the power back-off
value 372.
[0069] In an additional aspect, load balancing component 320 may
optionally include comparing component 360, which may be configured
to compare the frequency measurements 332 with power thresholds.
For example, comparing component 360 may compare measurements of
intra-frequency RSRP 336 and RSRQ 338 levels and measurements of
inter-frequency RSRP 342 and RSRQ 344 levels that UE 302 made with
a power threshold 362 in order to determine whether the
measurements in the licensed spectrum 334 satisfy the licensed
power threshold 362, and whether the measurements in the unlicensed
spectrum 340 satisfy the unlicensed power threshold 364. In some
instances, UE 302 may be located within cell coverage of network
entity 304, but only within coverage of the licensed spectrum 334
and not of the unlicensed spectrum 340. As such, comparing
component 360 compares measurements of intra-frequency RSRP 336 and
RSRQ 338 levels with the licensed power threshold 362 in order to
determine that there is sufficient cell coverage in the licensed
spectrum 334 provided by network entity 304. Further, comparing
component 360 compares measurements of inter-frequency RSRP 342 and
RSRQ 344 levels with unlicensed power threshold 364 in order to
determine that there is sufficient cell coverage n the unlicensed
spectrum 340 provided by network entity 304. Comparing component
360 prevents UE 302 from unnecessarily selecting network entity 304
when UE 302 is not located within range of the cell coverage
provided by network entity 304 in the unlicensed spectrum 340 even
if network entity 304 provides cell coverage in the licensed
spectrum 334.
[0070] As a result, comparing component 360 may be configured to
place one or more UEs (e.g., UE 302) into an offload set 366 based
on comparing the frequency measurements 332 with the power
thresholds. If the frequency measurements 332 of a specific UE
(e.g., UE 302) satisfy both licensed power threshold 362 and
unlicensed power threshold 364 then comparing component 360 places
that specific UE into offload set 366. In some instances, offload
set 366 designates UEs (e.g., UE 302) that are to be offloaded onto
a neighbor cell (e.g., network entity 304) as a result of adjusting
the cell coverage of network entity 306. UEs not placed into the
offload set 366 are designated as UEs that will remain within cell
coverage of network entity 306 even after cell coverage 382 is
adjusted.
[0071] In another aspect, load balancing component 320 may include
calculating component 370, which may be configured to calculate a
power back-off value 372. For example, calculating component 370
may calculate a power back-off value 372 corresponding to one or
more neighbor cells based on the plurality of frequency
measurements 332. In some instances, calculating component 370 may
calculate the power back-off value 372 based on measurements of
intra-frequency RSRP 336 and RSRQ 338 levels and measurements of
inter-frequency RSRP 342 and RSRQ 344 levels that UE 302 made. In
other instances, calculating component 370 may calculate the power
back-off value 372 in order for a predetermined percentage and/or
number of UEs to no longer be within cell coverage of network
entity 306. The power back-off value 372 may be used to adjust the
cell coverage 382 of network entity 306. In an instance, a positive
power back-off value 372 may decrease the cell coverage 382 of
network entity 306 where as a negative power back-off value 372 may
increase the cell coverage 382 of network entity 306. Decreasing
the cell coverage 382 may decrease the physical area that network
entity 306 provides cell coverage. The power back-off value 372 may
be calculated in relation to the number of UEs within cell coverage
382 of network entity 306 and the index of the strongest neighbor
cell in terms of intra-frequency signal strength. Calculating
component 370 may calculate the power back-off value 372 for each
neighbor cell (e.g., network entity 304). Each neighbor cell may be
determined based on measurements of intra-frequency RSRP 336 and
RSRQ 338 levels and measurements of inter-frequency RSRP 342 and
RSRQ 344 levels that each UE (e.g., UE 302) made. For instance, UE
302 may have made a plurality of frequency measurements 332
including frequency measurements 332 for one or more neighbor
cells. The plurality of frequency measurements 332 may comprise an
indication as to which neighbor cell they are associated with, so
that the plurality of frequency measurements 332 that the plurality
of UEs made may be correctly associated with one or more neighbor
cells. As a result, each power back-off value 372 may be compared
in order to determine the strongest neighbor cell. In an optional
instance, calculating component 370 may be configured to calculate
the one or more power back-off values 372 based only on the UEs
within the offload set 366. As such, only the UEs designated to be
offloaded from cell coverage 382 of network entity 306 may be used
to calculate the power back-off value 372. Calculating component
370 may be configured not to take into consideration UEs designated
to remain within cell coverage 382 of network entity 306 when
calculating the one or more power back-off values 372.
[0072] In a further aspect, load balancing component 320 may
include coverage component 380, which may be configured to adjust
the cell coverage 382 of network entity 306 based on the power
back-off value 372 such that one or more UEs (e.g., UE 302) are
outside the cell coverage 382. For example, coverage component 380
may adjust the transmit power 384 based on the power back-off value
372. In an instance, power back-off value 372 may be a positive
value (e.g., greater than zero), and thereby cause the transmit
power 384 to decrease in value. As a result of the transmit power
384 decreasing in value, cell coverage 382 will be reduced since
cell coverage is directly proportional to transmit power. The level
of reduction in cell coverage 382 based on the power back-off value
372 may correspond to the calculated percentage and/or number of
UEs determined to be offloaded onto a neighbor cell (e.g., network
entity 304). For instance, the cell coverage 382 may be adjust so
that the calculated percentage and/or number of UEs within licensed
and unlicensed cell coverage of a neighbor cell (e.g., network
entity 304) are no longer served by network entity 306. As such,
the one or more UEs (e.g., UE 302) may be free to attach to the
neighbor cell (e.g., network entity 304). As a result, the one or
more UEs (e.g., UE 302) will be able to utilize both the licensed
spectrum 334 and unlicensed spectrum 340 provided by neighbor cell
(e.g., network entity 304).
[0073] FIG. 6 is a diagram 400 illustrating a range expanded
cellular region (e.g., cell coverage) in a heterogeneous network
(Hetnet). A network entity 306 including load balancing component
320 as in FIG. 4, may have a range reduction cellular region 403
that is reduced or decreased from the cellular region 401 through a
power management coordination, and optionally enhanced inter-cell
interference coordination between a lower power class eNB such as a
network entity 304 and the macro network entity 306 and through
interference cancelation performed by the UE 302. In enhanced power
management coordination, the network entity 306 receives
information from the UE 302 regarding frequency measurements. The
information allows the network entity 304 to serve the UE 302 in
the cellular region 402 and to accept a handoff of the UE 302 from
the macro network entity 306 as the UE 302 leaves the range reduced
cellular region 403 and enters region 402. In this example, when
the UE 302 leaves the range reduced region 403 (e.g., LTE/LTE
Advanced over licensed spectrum coverage area) and enters region
402, the UE 302 may be provided with access to the network entity
304 via both LTE/LTE Advanced over licensed spectrum and LTE/LTE
Advanced over unlicensed spectrum).
[0074] FIG. 7 is a diagram 410 illustrating a carrier aggregation
(CA) network. A network entity 306 including load balancing
component 320 as in FIG. 4 provides licensed spectrum 411 and
unlicensed spectrum 412 uplink and downlink coverage to a UE 302.
In a CA network, a UE (e.g., UE 302) that is in cellular region 413
may be served by network entity 304, and have licensed uplink and
downlink coverage that are supplemented or aggregated with by
unlicensed uplink and downlink coverage.
[0075] FIG. 8 is a diagram 420 illustrating a supplementary
downlink (SDL) network. A network entity 304, similar to or the
same as network entity 306 including load balancing component 320
as in FIG. 4 provides licensed spectrum 421 uplink and downlink
coverage and unlicensed spectrum 422 downlink coverage to a UE 302.
In a SDL network, a UE (e.g., UE 302) that is in cellular region
423 may be served by network entity 304, and have licensed uplink
and downlink coverage that are supplemented by unlicensed downlink
coverage.
[0076] Referring to FIGS. 9 and 10, the methods are shown and
described as a series of acts for purposes of simplicity of
explanation. However, it is to be understood and appreciated that
the methods (and further methods related thereto) are not limited
by the order of acts, as some acts may, in accordance with one or
more aspects, occur in different orders and/or concurrently with
other acts from that shown and described herein. For example, it is
to be appreciated that the methods may alternatively be represented
as a series of interrelated states or events, such as in a state
diagram. Moreover, not all illustrated acts may be required to
implement a method in accordance with one or more features
described herein.
[0077] FIG. 9 is a flow chart 500 of a method of wireless
communication. The method may be performed by a network entity,
such as network entity 306 including load balancing component 320
as in FIG. 4, for adjusting a cell coverage of the network entity
in order to permit a UE (e.g., UE 302) to attach to a network
entity 304 providing coverage in both a licensed spectrum 334 and
unlicensed spectrum 340.
[0078] In an aspect, at block 510, method 500 may include
determining that one or more user equipments (UEs) that are served
by a primary network entity providing coverage in a licensed
spectrum are within coverage in both a licensed spectrum and
unlicensed spectrum of a secondary network entity. For example, as
described herein, load balancing component 320 (FIG. 4) may be
configured to determine that one or more UEs (e.g., UE 302) that
are served by a primary network entity (e.g., network entity 306)
providing cell coverage 382 in a licensed spectrum 334 are within
coverage in both a licensed spectrum 334 and unlicensed spectrum
340 of a secondary network entity (e.g., network entity 304).
[0079] Further, at block 520, method 500 may include adjusting the
coverage of the primary network entity in order for the one or more
UEs to be able to attach to the secondary network entity. For
example, as described herein, load balancing component 320 (FIG. 4)
may be configured to adjust the cell coverage of the primary
network entity (e.g., network entity 306) in order for the one or
more UEs (e.g., UE 302) to be able to attach to the secondary
network entity (e.g., network entity 304).
[0080] FIG. 10 is a flow chart 600 of a method of wireless
communication. The method may be performed by a network entity,
such as network entity 306 including load balancing component 320
as in FIG. 4, for adjusting a cell coverage of the network entity
in order to permit a UE (e.g., UE 302) to attach to a network
entity 304 providing coverage in both a licensed spectrum 334 and
unlicensed spectrum 340.
[0081] In an aspect, at block 610, method 600 may include
requesting one or more UEs to perform a plurality of frequency
measurements. For example, as described herein, load balancing
component 320 may execute requesting component 330 to request one
or more UEs (e.g., UE 302) to perform a plurality of frequency
measurements 332 on both the licensed spectrum 334 and unlicensed
spectrum 340 for one or more cells (e.g., cell coverage provided by
network entity 304). For example, measurements may include
intra-frequency RSRP levels 336, inter-frequency RSRP levels 342,
intra-frequency RSRQ levels 338, and inter-frequency RSRQ levels
344.
[0082] In a further aspect, at block 620, method 600 may optionally
include determining based on the plurality of frequency
measurements, whether the one or more UEs have access to a second
network entity over both the licensed spectrum and the unlicensed
spectrum. For example, as described herein, load balancing
component 320 may execute determining component 350 to determine
based on the plurality of frequency measurements 332, whether the
one or more UEs (e.g., UE 302) have access to a second network
entity (e.g., network entity 304) over both the licensed spectrum
334 and the unlicensed spectrum 340. If one or more UEs (e.g., UE
302) do not have access to a second network entity (e.g., network
entity 304) over both the licensed spectrum 334 and the unlicensed
spectrum 340 then method 600 returns to block 610.
[0083] However, if one or more UEs (e.g., UE 302) have access to a
second network entity (e.g., network entity 304) over both the
licensed spectrum 334 and the unlicensed spectrum 340 then method
600 proceeds to block 630. In an aspect, at block 630, method 600
may optionally include determining whether the measurements in the
licensed spectrum meet or exceed a first threshold and whether the
measurements in the unlicensed spectrum meet or exceed a second
threshold. For example, as described herein, load balancing
component 320 may execute comparing component 360 to determine
whether the measurements in the licensed spectrum 334 meet or
exceed a first threshold (e.g., licensed power threshold 362) and
whether the measurements in the unlicensed spectrum 340 meet or
exceed a second threshold (e.g., unlicensed power threshold 364).
If the measurements in the licensed spectrum 334 fail to meet or
exceed a first threshold (e.g., licensed power threshold 362) and
if the measurements in the unlicensed spectrum 340 fail to meet or
exceed a second threshold (e.g., unlicensed power threshold 364)
then method 600 returns to block 610.
[0084] However, if the measurements in the licensed spectrum 334
meet or exceed a first threshold (e.g., licensed power threshold
362) and if the measurements in the unlicensed spectrum 340 meet or
exceed a second threshold (e.g., unlicensed power threshold 364)
then method 600 proceed to block 640. In an aspect, at block 640,
method 600 may include calculating a power back-off value based on
the plurality of frequency measurements. For example, as described
herein, load balancing component 320 may execute calculating
component 370 to calculate a power back-off value 372 based on the
plurality of frequency measurements 332.
[0085] In an aspect, at block 650, method 600 includes adjusting a
cell coverage based at least in part on the power back-off value.
For example, as described herein, load balancing component 320 may
execute coverage component 380 to adjust a cell coverage 382 of a
network entity (e.g., network entity 306) based at least in part on
the power back-off value 372. Specifically, for example, coverage
component 380 may be configured to adjust (e.g., reduce) the
transmit power 384, so one or more UEs (e.g., UE 302) may no longer
be located in cell coverage 382 of the network entity (e.g.,
network entity 306). As such, the one or more UEs (e.g., UE 302)
may be free to attach to a neighbor cell, such as network entity
304. As a result, the one or more UEs (e.g., UE 302) will be able
to utilize both licensed spectrum 334 and unlicensed spectrum 340
provided by network entity 304.
[0086] FIG. 11 illustrates several sample components (represented
by corresponding blocks) that may be incorporated into an apparatus
702 corresponding to UE 302 (FIG. 4), an apparatus 704
corresponding to network entity 304/306, which may include load
balancing component 320, and an apparatus 706 (e.g., corresponding
to an access terminal, an access point, and a network entity,
respectively) to support communication adaptation operations as
taught herein. It should be appreciated that these components may
be implemented in different types of apparatuses in different
implementations (e.g., in an ASIC, in an SoC, etc.). The described
components also may be incorporated into other apparatuses in a
communication system. For example, other apparatuses in a system
may include components similar to those described to provide
similar functionality. Also, a given apparatus may contain one or
more of the described components. For example, an apparatus may
include multiple transceiver components that enable the apparatus
to operate on multiple carriers and/or communicate via different
technologies.
[0087] The apparatus 702 and the apparatus 704 each include at
least one wireless communication device (represented by the
communication devices 708 and 714 (and the communication device 720
if the apparatus 704 is a relay)) for communicating with other
nodes via at least one designated radio access technology. Each
communication device 708 includes at least one transmitter
(represented by the transmitter 710) for transmitting and encoding
signals (e.g., messages, indications, information, and so on) and
at least one receiver (represented by the receiver 712) for
receiving and decoding signals (e.g., messages, indications,
information, pilots, and so on). Similarly, each communication
device 714 includes at least one transmitter (represented by the
transmitter 716) for transmitting signals (e.g., messages,
indications, information, pilots, and so on) and at least one
receiver (represented by the receiver 718) for receiving signals
(e.g., messages, indications, information, and so on). If the
apparatus 704 is a relay access point, each communication device
720 may include at least one transmitter (represented by the
transmitter 722) for transmitting signals (e.g., messages,
indications, information, pilots, and so on) and at least one
receiver (represented by the receiver 724) for receiving signals
(e.g., messages, indications, information, and so on).
[0088] A transmitter and a receiver may comprise an integrated
device (e.g., embodied as a transmitter circuit and a receiver
circuit of a single communication device) in some implementations,
may comprise a separate transmitter device and a separate receiver
device in some implementations, or may be embodied in other ways in
other implementations. In some aspects, a wireless communication
device (e.g., one of multiple wireless communication devices) of
the apparatus 704 comprises a network listen module.
[0089] The apparatus 706 (and the apparatus 704 if it is not a
relay access point) includes at least one communication device
(represented by the communication device 726 and, optionally, 720)
for communicating with other nodes. For example, the communication
device 726 may comprise a network interface that is configured to
communicate with one or more network entities via a wire-based or
wireless backhaul. In some aspects, the communication device 726
may be implemented as a transceiver configured to support
wire-based or wireless signal communication. This communication may
involve, for example, sending and receiving: messages, parameters,
or other types of information. Accordingly, in the example of FIG.
11, the communication device 726 is shown as comprising a
transmitter 728 and a receiver 730. Similarly, if the apparatus 704
is not a relay access point, the communication device 720 may
comprise a network interface that is configured to communicate with
one or more network entities via a wire-based or wireless backhaul.
As with the communication device 726, the communication device 720
is shown as comprising a transmitter 722 and a receiver 724.
[0090] The apparatuses 702, 704, and 706 also include other
components that may be used in conjunction with communication
adaptation operations as taught herein. The apparatus 702 includes
a processing system 732 for providing functionality relating to,
for example, communicating with an access point to support
communication adaptation as taught herein and for providing other
processing functionality. The apparatus 704 includes a processing
system 734 for providing functionality relating to, for example,
communication adaptation as taught herein and for providing other
processing functionality. The apparatus 706 includes a processing
system 736 for providing functionality relating to, for example,
communication adaptation as taught herein and for providing other
processing functionality. The apparatuses 702, 704, and 706 include
memory devices 738, 740, and 742 (e.g., each including a memory
device), respectively, for maintaining information (e.g.,
information indicative of reserved resources, thresholds,
parameters, and so on). In addition, the apparatuses 702, 704, and
706 include user interface devices 744, 746, and 748, respectively,
for providing indications (e.g., audible and/or visual indications)
to a user and/or for receiving user input (e.g., upon user
actuation of a sensing device such a keypad, a touch screen, a
microphone, and so on).
[0091] For convenience, the apparatus 702 is shown in FIG. 11 as
including components that may be used in the various examples
described herein. In practice, the illustrated blocks may have
different functionality in different aspects.
[0092] The components of FIG. 11 may be implemented in various
ways. In some implementations, the components of FIG. 11 may be
implemented in one or more circuits such as, for example, one or
more processors and/or one or more ASICs (which may include one or
more processors). Here, each circuit may use and/or incorporate at
least one memory component for storing information or executable
code used by the circuit to provide this functionality. For
example, some or all of the functionality represented by blocks
708, 732, 738, and 744 may be implemented by processor and memory
component(s) of the apparatus 702 (e.g., by execution of
appropriate code and/or by appropriate configuration of processor
components). Similarly, some or all of the functionality
represented by blocks 714, 720, 734, 740, and 746 may be
implemented by processor and memory component(s) of the apparatus
704 (e.g., by execution of appropriate code and/or by appropriate
configuration of processor components). Also, some or all of the
functionality represented by blocks 726, 736, 742, and 748 may be
implemented by processor and memory component(s) of the apparatus
706 (e.g., by execution of appropriate code and/or by appropriate
configuration of processor components).
[0093] Some of the access points referred to herein may comprise
low-power access points. In a typical network, low-power access
points (e.g., femto cells) are deployed to supplement conventional
network access points (e.g., macro access points). For example, a
low-power access point installed in a user's home or in an
enterprise environment (e.g., commercial buildings) may provide
voice and high speed data service for access terminals supporting
cellular radio communication (e.g., CDMA, WCDMA, UMTS, LTE, etc.).
In general, these low-power access points provide more robust
coverage and higher throughput for access terminals in the vicinity
of the low-power access points.
[0094] As used herein, the term low-power access point refers to an
access point having a transmit power (e.g., one or more of: maximum
transmit power, instantaneous transmit power, nominal transmit
power, average transmit power, or some other form of transmit
power) that is less than a transmit power (e.g., as defined above)
of any macro access point in the coverage area. In some
implementations, each low-power access point has a transmit power
(e.g., as defined above) that is less than a transmit power (e.g.,
as defined above) of the macro access point by a relative margin
(e.g., 10 dBm or more). In some implementations, low-power access
points such as femto cells may have a maximum transmit power of 20
dBm or less. In some implementations, low-power access points such
as pico cells may have a maximum transmit power of 24 dBm or less.
It should be appreciated, however, that these or other types of
low-power access points may have a higher or lower maximum transmit
power in other implementations (e.g., up to 1 Watt in some cases,
up to 10 Watts in some cases, and so on).
[0095] Typically, low-power access points connect to the Internet
via a broadband connection (e.g., a digital subscriber line (DSL)
router, a cable modem, or some other type of modem) that provides a
backhaul link to a mobile operator's network. Thus, a low-power
access point deployed in a user's home or business provides mobile
network access to one or more devices via the broadband
connection.
[0096] Various types of low-power access points may be employed in
a given system. For example, low-power access points may be
implemented as or referred to as femto cells, femto access points,
small cells, femto nodes, home NodeBs (HNBs), home eNodeBs (HeNBs),
access point base stations, pico cells, pico nodes, or micro
cells.
[0097] For convenience, low-power access points may be referred to
simply as small cells in the discussion that follows. Thus, it
should be appreciated that any discussion related to small cells
herein may be equally applicable to low-power access points in
general (e.g., to femto cells, to micro cells, to pico cells,
etc.).
[0098] Small cells may be configured to support different types of
access modes. For example, in an open access mode, a small cell may
allow any access terminal to obtain any type of service via the
small cell. In a restricted (or closed) access mode, a small cell
may only allow authorized access terminals to obtain service via
the small cell. For example, a small cell may only allow access
terminals (e.g., so called home access terminals) belonging to a
certain subscriber group (e.g., a closed subscriber group (CSG)) to
obtain service via the small cell. In a hybrid access mode, alien
access terminals (e.g., non-home access terminals, non-CSG access
terminals) may be given limited access to the small cell. For
example, a macro access terminal that does not belong to a small
cell's CSG may be allowed to access the small cell only if
sufficient resources are available for all home access terminals
currently being served by the small cell.
[0099] Thus, small cells operating in one or more of these access
modes may be used to provide indoor coverage and/or extended
outdoor coverage. By allowing access to users through adoption of a
desired access mode of operation, small cells may provide improved
service within the coverage area and potentially extend the service
coverage area for users of a macro network.
[0100] Thus, in some aspects the teachings herein may be employed
in a network that includes macro scale coverage (e.g., a large area
cellular network such as a third generation (3G) network, typically
referred to as a macro cell network or a WAN) and smaller scale
coverage (e.g., a residence-based or building-based network
environment, typically referred to as a LAN). As an access terminal
(AT) moves through such a network, the access terminal may be
served in certain locations by access points that provide macro
coverage while the access terminal may be served at other locations
by access points that provide smaller scale coverage. In some
aspects, the smaller coverage nodes may be used to provide
incremental capacity growth, in-building coverage, and different
services (e.g., for a more robust user experience).
[0101] In the description herein, a node (e.g., an access point)
that provides coverage over a relatively large area may be referred
to as a macro access point while a node that provides coverage over
a relatively small area (e.g., a residence) may be referred to as a
small cell. It should be appreciated that the teachings herein may
be applicable to nodes associated with other types of coverage
areas. For example, a pico access point may provide coverage (e.g.,
coverage within a commercial building) over an area that is smaller
than a macro area and larger than a femto cell area. In various
applications, other terminology may be used to reference a macro
access point, a small cell, or other access point-type nodes. For
example, a macro access point may be configured or referred to as
an access node, base station, access point, eNodeB, macro cell, and
so on. In some implementations, a node may be associated with
(e.g., referred to as or divided into) one or more cells or
sectors. A cell or sector associated with a macro access point, a
femto access point, or a pico access point may be referred to as a
macro cell, a femto cell, or a pico cell, respectively.
[0102] FIG. 12 illustrates a wireless communication system 800,
configured to support a number of users, in which the teachings
herein may be implemented. The system 800 provides communication
for multiple cells 802, such as, for example, macro cells
802A-802G, with each cell being serviced by a corresponding access
point 804 (e.g., access points 804A-804G), each of which may
include load balancing component 320 (FIG. 4) configured to adjust
a cell coverage of an access point (e.g., network entity 306) that
only provides coverage in the licensed spectrum, so as to provide
an access terminal (e.g., UE 302 in FIG. 4) with the capability of
attaching to another access point (e.g., network entity 304 in FIG.
4) that provides coverage in both the licensed spectrum and the
unlicensed spectrum. As shown in FIG. 12, access terminals 806
(e.g., access terminals 806A-806L) may be dispersed at various
locations throughout the system over time. Each access terminal 806
may communicate with one or more access points 804 on a forward
link (FL) and/or a reverse link (RL) at a given moment, depending
upon whether the access terminal 806 is active and whether it is in
soft handoff, for example. The wireless communication system 800
may provide service over a large geographic region. For example,
macro cells 802A-802G may cover a few blocks in a neighborhood or
several miles in a rural environment.
[0103] FIG. 13 illustrates an example of a communication system 900
where one or more small cells are deployed within a network
environment. Specifically, the system 900 includes multiple small
cells 910 (e.g., small cells 910A and 910B) installed in a
relatively small scale network environment (e.g., in one or more
user residences 930). Each small cell 910 may be coupled to a wide
area network 940 (e.g., the Internet) and a mobile operator core
network 950 via a DSL router, a cable modem, a wireless link, or
other connectivity means (not shown). As will be discussed below,
each small cell 910 may be configured to serve associated access
terminals 920 (e.g., access terminal 920A) and, optionally, other
(e.g., hybrid or alien) access terminals 920 (e.g., access terminal
920B). In other words, access to small cells 910 may be restricted
whereby a given access terminal 920 may be served by a set of
designated (e.g., home) small cell(s) 910 but may not be served by
any non-designated small cells 910 (e.g., a neighbor's small cell
910).
[0104] FIG. 14 illustrates an example of a coverage map 1000 where
several tracking areas 1002 (or routing areas or location areas)
are defined, each of which includes several macro coverage areas
1004. Here, areas of coverage associated with tracking areas 1002A,
1002B, and 1002C are delineated by the wide lines and the macro
coverage areas 1004 are represented by the larger hexagons. The
tracking areas 1002 also include femto coverage areas 1006. In this
example, each of the femto coverage areas 1006 (e.g., femto
coverage areas 1006B and 1006C) is depicted within one or more
macro coverage areas 1004 (e.g., macro coverage areas 1004A and
1004B). It should be appreciated, however, that some or all of a
femto coverage area 1006 might not lie within a macro coverage area
1004. In practice, a large number of femto coverage areas 1006
(e.g., femto coverage areas 1006A and 1006D) may be defined within
a given tracking area 1002 or macro coverage area 1004. Also, one
or more pico coverage areas (not shown) may be defined within a
given tracking area 1002 or macro coverage area 1004.
[0105] Referring again to FIG. 13, the owner of a small cell 910
may subscribe to mobile service, such as, for example, 3G mobile
service, offered through the mobile operator core network 950. In
addition, an access terminal 920 may be capable of operating both
in macro environments and in smaller scale (e.g., residential)
network environments. In other words, depending on the current
location of the access terminal 920, the access terminal 920 may be
served by a macro cell access point 960 associated with the mobile
operator core network 950 or by any one of a set of small cells 910
(e.g., the small cells 910A and 910B that reside within a
corresponding user residence 930). For example, when a subscriber
is outside his home, he is served by a standard macro access point
(e.g., access point 960), which may include load balancing
component 320 (FIG. 4) configured to adjust a cell coverage of an
access point (e.g., network entity 306) that only provides coverage
in the licensed spectrum, so as to provide an access terminal
(e.g., UE 302 in FIG. 4) with the capability of attaching to
another access point (e.g., network entity 304 in FIG. 4) that
provides coverage in both the licensed spectrum and the unlicensed
spectrum, and when the subscriber is at home, he is served by a
small cell (e.g., small cell 910A). Here, a small cell 910 may be
backward compatible with legacy access terminals 920.
[0106] A small cell 910 may be deployed on a single frequency or,
in the alternative, on multiple frequencies. Depending on the
particular configuration, the single frequency or one or more of
the multiple frequencies may overlap with one or more frequencies
used by a macro access point (e.g., access point 960).
[0107] In some aspects, an access terminal 920 may be configured to
connect to a preferred small cell (e.g., the home small cell of the
access terminal 920) whenever such connectivity is possible. For
example, whenever the access terminal 920A is within the user's
residence 930, it may be desired that the access terminal 920A
communicate only with the home small cell 910A or 910B.
[0108] In some aspects, if the access terminal 920 operates within
the macro cellular network 950 but is not residing on its most
preferred network (e.g., as defined in a preferred roaming list),
the access terminal 920 may continue to search for the most
preferred network (e.g., the preferred small cell 910) using a
better system reselection (BSR) procedure, which may involve a
periodic scanning of available systems to determine whether better
systems are currently available and subsequently acquire such
preferred systems. The access terminal 920 may limit the search for
specific band and channel. For example, one or more femto channels
may be defined whereby all small cells (or all restricted small
cells) in a region operate on the femto channel(s). The search for
the most preferred system may be repeated periodically. Upon
discovery of a preferred small cell 910, the access terminal 920
selects the small cell 910 and registers on it for use when within
its coverage area.
[0109] Access to a small cell may be restricted in some aspects.
For example, a given small cell may only provide certain services
to certain access terminals. In deployments with so-called
restricted (or closed) access, a given access terminal may only be
served by the macro cell mobile network and a defined set of small
cells (e.g., the small cells 910 that reside within the
corresponding user residence 930). In some implementations, an
access point may be restricted to not provide, for at least one
node (e.g., access terminal), at least one of: signaling, data
access, registration, paging, or service.
[0110] In some aspects, a restricted small cell (which may also be
referred to as a Closed Subscriber Group Home NodeB) is one that
provides service to a restricted provisioned set of access
terminals. This set may be temporarily or permanently extended as
necessary. In some aspects, a Closed Subscriber Group (CSG) may be
defined as the set of access points (e.g., small cells) that share
a common access control list of access terminals.
[0111] Various relationships may thus exist between a given small
cell and a given access terminal. For example, from the perspective
of an access terminal, an open small cell may refer to a small cell
with unrestricted access (e.g., the small cell allows access to any
access terminal). A restricted small cell may refer to a small cell
that is restricted in some manner (e.g., restricted for access
and/or registration). A home small cell may refer to a small cell
on which the access terminal is authorized to access and operate on
(e.g., permanent access is provided for a defined set of one or
more access terminals). A hybrid (or guest) small cell may refer to
a small cell on which different access terminals are provided
different levels of service (e.g., some access terminals may be
allowed partial and/or temporary access while other access
terminals may be allowed full access). An alien small cell may
refer to a small cell on which the access terminal is not
authorized to access or operate on, except for perhaps emergency
situations (e.g., emergency-911 calls).
[0112] From a restricted small cell perspective, a home access
terminal may refer to an access terminal that is authorized to
access the restricted small cell installed in the residence of that
access terminal's owner (usually the home access terminal has
permanent access to that small cell). A guest access terminal may
refer to an access terminal with temporary access to the restricted
small cell (e.g., limited based on deadline, time of use, bytes,
connection count, or some other criterion or criteria). An alien
access terminal may refer to an access terminal that does not have
permission to access the restricted small cell, except for perhaps
emergency situations, for example, such as 911 calls (e.g., an
access terminal that does not have the credentials or permission to
register with the restricted small cell).
[0113] For convenience, the disclosure herein describes various
functionality in the context of a small cell. It should be
appreciated, however, that a pico access point may provide the same
or similar functionality for a larger coverage area. For example, a
pico access point may be restricted, a home pico access point may
be defined for a given access terminal, and so on.
[0114] The teachings herein may be employed in a wireless
multiple-access communication system that simultaneously supports
communication for multiple wireless access terminals. Here, each
terminal may communicate with one or more access points via
transmissions on the forward and reverse links. The forward link
(or downlink) refers to the communication link from the access
points to the terminals, and the reverse link (or uplink) refers to
the communication link from the terminals to the access points.
This communication link may be established via a
single-in-single-out system, a multiple-in-multiple-out (MIMO)
system, or some other type of system.
[0115] A MIMO system employs multiple (N.sub.T) transmit antennas
and multiple (N.sub.R) receive antennas for data transmission. A
MIMO channel formed by the N.sub.T transmit and N.sub.R receive
antennas may be decomposed into N.sub.S independent channels, which
are also referred to as spatial channels, where N.sub.S.ltoreq.min
{N.sub.T, N.sub.R}. Each of the N.sub.S independent channels
corresponds to a dimension. The MIMO system may provide improved
performance (e.g., higher throughput and/or greater reliability) if
the additional dimensionalities created by the multiple transmit
and receive antennas are utilized.
[0116] A MIMO system may support time division duplex (TDD) and
frequency division duplex (FDD). In a TDD system, the forward and
reverse link transmissions are on the same frequency region so that
the reciprocity principle allows the estimation of the forward link
channel from the reverse link channel. This enables the access
point to extract transmit beam-forming gain on the forward link
when multiple antennas are available at the access point.
[0117] FIG. 15 illustrates in more detail the components of a
wireless device 1110 (e.g., a small cell AP), which may include
load balancing component 320 (FIG. 4) configured to adjust a cell
coverage of an access point (e.g., network entity 306) that only
provides coverage in the licensed spectrum, so as to provide an
access terminal (e.g., UE 302 in FIG. 4) with the capability of
attaching to another access point (e.g., network entity 304 in FIG.
4) that provides coverage in both the licensed spectrum and the
unlicensed spectrum, and a wireless device 1150 (e.g., a UE) of a
sample communication system 1100 that may be adapted as described
herein. At the device 1110, traffic data for a number of data
streams is provided from a data source 1112 to a transmit (TX) data
processor 1114. Each data stream may then be transmitted over a
respective transmit antenna.
[0118] The TX data processor 1114 formats, codes, and interleaves
the traffic data for each data stream based on a particular coding
scheme selected for that data stream to provide coded data. The
coded data for each data stream may be multiplexed with pilot data
using OFDM techniques. The pilot data is typically a known data
pattern that is processed in a known manner and may be used at the
receiver system to estimate the channel response. The multiplexed
pilot and coded data for each data stream is then modulated (i.e.,
symbol mapped) based on a particular modulation scheme (e.g., BPSK,
QSPK, M-PSK, or M-QAM) selected for that data stream to provide
modulation symbols. The data rate, coding, and modulation for each
data stream may be determined by instructions performed by a
processor 1130. A data memory 1132 may store program code, data,
and other information used by the processor 1130 or other
components of the device 1110.
[0119] The modulation symbols for all data streams are then
provided to a TX MIMO processor 1120, which may further process the
modulation symbols (e.g., for OFDM). The TX MIMO processor 1120
then provides NT modulation symbol streams to NT transceivers
(XCVR) 1122A through 1122T. In some aspects, the TX MIMO processor
1120 applies beam-forming weights to the symbols of the data
streams and to the antenna from which the symbol is being
transmitted.
[0120] Each transceiver 1122 receives and processes a respective
symbol stream to provide one or more analog signals, and further
conditions (e.g., amplifies, filters, and upconverts) the analog
signals to provide a modulated signal suitable for transmission
over the MIMO channel. NT modulated signals from transceivers 1122A
through 1122T are then transmitted from NT antennas 1124A through
1124T, respectively.
[0121] At the device 1150, the transmitted modulated signals are
received by NR antennas 1152A through 1152R and the received signal
from each antenna 1152 is provided to a respective transceiver
(XCVR) 1154A through 1154R. Each transceiver 1154 conditions (e.g.,
filters, amplifies, and downconverts) a respective received signal,
digitizes the conditioned signal to provide samples, and further
processes the samples to provide a corresponding "received" symbol
stream.
[0122] A receive (RX) data processor 1160 then receives and
processes the NR received symbol streams from NR transceivers 1154
based on a particular receiver processing technique to provide NT
"detected" symbol streams. The RX data processor 1160 then
demodulates, deinterleaves, and decodes each detected symbol stream
to recover the traffic data for the data stream. The processing by
the RX data processor 1160 is complementary to that performed by
the TX MIMO processor 1120 and the TX data processor 1114 at the
device 1110.
[0123] A processor 1170 periodically determines which pre-coding
matrix to use (discussed below). The processor 1170 formulates a
reverse link message comprising a matrix index portion and a rank
value portion. A data memory 1172 may store program code, data, and
other information used by the processor 1170 or other components of
the device 1150.
[0124] The reverse link message may comprise various types of
information regarding the communication link and/or the received
data stream. The reverse link message is then processed by a TX
data processor 1138, which also receives traffic data for a number
of data streams from a data source 1136, modulated by a modulator
1180, conditioned by the transceivers 1154A through 1154R, and
transmitted back to the device 1110.
[0125] At the device 1110, the modulated signals from the device
1150 are received by the antennas 1124, conditioned by the
transceivers 1122, demodulated by a demodulator (DEMOD) 1140, and
processed by a RX data processor 1142 to extract the reverse link
message transmitted by the device 1150. The processor 1130 then
determines which pre-coding matrix to use for determining the
beam-forming weights then processes the extracted message.
[0126] It will be appreciated that for each device 1110 and 1150
the functionality of two or more of the described components may be
provided by a single component. It will be also be appreciated that
the various communication components illustrated in FIG. 11 and
described above may be further configured as appropriate to perform
communication adaptation as taught herein. For example, the
processors 1130/1170 may cooperate with the memories 1132/1172
and/or other components of the respective devices 1110/1150 to
perform the communication adaptation as taught herein.
[0127] FIG. 16 illustrates an example access terminal apparatus
1200 represented as a series of interrelated functional modules. A
module for determining that one or more user equipments (UEs) that
are served by a primary network entity providing coverage in a
licensed spectrum are within coverage in both a licensed spectrum
and unlicensed spectrum of a secondary network entity 1202 may
correspond at least in some aspects to, for example, a processing
system as discussed herein. A module for adjusting the coverage of
the primary network entity in order for the one or more UEs to be
able to attach to the secondary network entity 1204 may correspond
at least in some aspects to, for example, a processing system as
discussed herein.
[0128] FIG. 17 illustrates an example access terminal apparatus
1300 represented as a series of interrelated functional modules. A
module for requesting one or more user equipments (UEs) to perform
a plurality of frequency measurements, wherein the plurality of
frequency measurements comprise measurements in a licensed spectrum
and an unlicensed spectrum 1302 may correspond at least in some
aspects to, for example, a processing system as discussed herein. A
module for determining, based on the plurality of frequency
measurements, whether the one or more UEs have access to a second
network entity over both the licensed spectrum and the unlicensed
spectrum 1304 may correspond at least in some aspects to, for
example, a processing system as discussed herein. A module for
determining whether the measurements in the licensed spectrum meet
or exceed a first threshold and whether the measurements in the
unlicensed spectrum meet or exceed a second threshold 1306 may
correspond at least in some aspects to, for example, a processing
system as discussed herein. A module for calculating a power
back-off value based on the plurality of frequency measurements
1308 may correspond at least in some aspects to, for example, a
processing system as discussed herein. A module for adjusting a
cell coverage based on the power back-off value such that the one
or more UEs are outside the cell coverage 1310 may correspond at
least in some aspects to, for example, a processing system as
discussed herein.
[0129] The functionality of the modules of FIGS. 16-17 may be
implemented in various ways consistent with the teachings herein.
In some aspects, the functionality of these modules may be
implemented as one or more electrical components. In some aspects,
the functionality of these blocks may be implemented as a
processing system including one or more processor components. In
some aspects, the functionality of these modules may be implemented
using, for example, at least a portion of one or more integrated
circuits (e.g., an ASIC). As discussed herein, an integrated
circuit may include a processor, software, other related
components, or some combination thereof. Thus, the functionality of
different modules may be implemented, for example, as different
subsets of an integrated circuit, as different subsets of a set of
software modules, or a combination thereof. Also, it should be
appreciated that a given subset (e.g., of an integrated circuit
and/or of a set of software modules) may provide at least a portion
of the functionality for more than one module.
[0130] In addition, the components and functions represented by
FIGS. 16-17 as well as other components and functions described
herein, may be implemented using any suitable means. Such means
also may be implemented, at least in part, using corresponding
structure as taught herein. For example, the components described
above in conjunction with the "module for" components of FIGS.
16-17 also may correspond to similarly designated "means for"
functionality. Thus, in some aspects one or more of such means may
be implemented using one or more of processor components,
integrated circuits, or other suitable structure as taught
herein.
[0131] In some aspects, an apparatus or any component of an
apparatus may be configured to (or operable to or adapted to)
provide functionality as taught herein. This may be achieved, for
example: by manufacturing (e.g., fabricating) the apparatus or
component so that it will provide the functionality; by programming
the apparatus or component so that it will provide the
functionality; or through the use of some other suitable
implementation technique. As one example, an integrated circuit may
be fabricated to provide the requisite functionality. As another
example, an integrated circuit may be fabricated to support the
requisite functionality and then configured (e.g., via programming)
to provide the requisite functionality. As yet another example, a
processor circuit may execute code to provide the requisite
functionality.
[0132] It should be understood that any reference to an element
herein using a designation such as "first," "second," and so forth
does not generally limit the quantity or order of those elements.
Rather, these designations may be used herein as a convenient
method of distinguishing between two or more elements or instances
of an element. Thus, a reference to first and second elements does
not mean that only two elements may be employed there or that the
first element must precede the second element in some manner. Also,
unless stated otherwise a set of elements may comprise one or more
elements. In addition, terminology of the form "at least one of A,
B, or C" or "one or more of A, B, or C" or "at least one of the
group consisting of A, B, and C" used in the description or the
claims means "A or B or C or any combination of these elements."
For example, this terminology may include A, or B, or C, or A and
B, or A and C, or A and B and C, or 2A, or 2B, or 2C, and so
on.
[0133] Those of skill in the art will appreciate that information
and signals may be represented using any of a variety of different
technologies and techniques. For example, data, instructions,
commands, information, signals, bits, symbols, and chips that may
be referenced throughout the above description may be represented
by voltages, currents, electromagnetic waves, magnetic fields or
particles, optical fields or particles, or any combination
thereof.
[0134] Further, those of skill in the art will appreciate that the
various illustrative logical blocks, modules, circuits, and
algorithm steps described in connection with the aspects disclosed
herein may be implemented as electronic hardware, computer
software, or combinations of both. To clearly illustrate this
interchangeability of hardware and software, various illustrative
components, blocks, modules, circuits, and steps have been
described above generally in terms of their functionality. Whether
such functionality is implemented as hardware or software depends
upon the particular application and design constraints imposed on
the overall system. Skilled artisans may implement the described
functionality in varying ways for each particular application, but
such implementation decisions should not be interpreted as causing
a departure from the scope of the present disclosure.
[0135] The methods, sequences and/or algorithms described in
connection with the aspects disclosed herein may be embodied
directly in hardware, in a software module executed by a processor,
or in a combination of the two. A software module may reside in RAM
memory, flash memory, ROM memory, EPROM memory, EEPROM memory,
registers, hard disk, a removable disk, a CD-ROM, or any other form
of storage medium known in the art. An exemplary storage medium is
coupled to the processor such that the processor can read
information from, and write information to, the storage medium. In
the alternative, the storage medium may be integral to the
processor.
[0136] Accordingly, an aspect of the disclosure can include a
computer readable medium embodying a method for requesting, by a
first network entity, one or more user equipments (UEs) to perform
a plurality of frequency measurements, wherein the plurality of
frequency measurements comprise measurements in a licensed spectrum
and measurements in an unlicensed spectrum; calculating, by the
first network entity, a power back-off value based on the plurality
of frequency measurements; and adjusting, by the first network
entity, a cell coverage based on the power back-off value such that
the one or more UEs are outside the cell coverage. Accordingly, the
disclosure is not limited to the illustrated examples.
[0137] While the foregoing disclosure shows illustrative aspects,
it should be noted that various changes and modifications could be
made herein without departing from the scope of the disclosure as
defined by the appended claims. The functions, steps and/or actions
of the method claims in accordance with the aspects of the
disclosure described herein need not be performed in any particular
order. Furthermore, although certain aspects may be described or
claimed in the singular, the plural is contemplated unless
limitation to the singular is explicitly stated.
* * * * *